The present invention relates to a towing tractor.
Japanese Unexamined Patent Application Publication No. 2011-98672 discloses a towing tractor that includes a frame extending in the longitudinal direction of the towing tractor and a counterweight connected to a rear part of the frame.
Among towing tractors of such type, some towing tractors are driven by an engine, and some others are driven by an electric motor. The motor-driven towing tractors include a type in which the driver's seat is positioned in the front part of the towing tractor and another type in which the driver's seat is disposed in the rear part of the towing tractor. The towing tractors of these types have been used widely in the airports and other places in accordance with the usage or preferences peculiar to the place where the towing tractor is used.
Conventionally, the frames for use in the towing tractors have been manufactured in various forms according to the type of the towing tractor, so that the designing, manufacturing and improvement of the towing tractors have involved many man-hours and time. Furthermore, because the frames for the towing tractors are generally long, large manufacturing facilities are required for manufacturing of the respective frames. This hinders reduction in the manufacturing cost of the conventional towing tractors.
Furthermore, the frames for the towing tractors have been made by connecting a plurality of various frame members by welding, which requires high skill and a long time. Such factor also makes it difficult to reduce the manufacturing cost of the conventional towing tractors. The strength of welded connection of the frame members may not be well controlled and, therefore, it is difficult to maintain the desired quality of the frames and hence the quality of the towing tractors.
The present invention which has been made in view of the above circumstances is directed to providing a towing tractor that enables reduction in the manufacturing cost while maintaining desired quality.